Readers reply: why haven’t we invented a way to record and play back smells?

I imagine that a couple of hundred years ago the idea of recording and playing back audio or video was as ridiculous as the idea seems now of recording and playing back odours. So why have we made so much progress at the first but none at the second? Peter Keyston, Newton Blossomville

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I presume the questioner has no sons. Anyone who has raised boys would consider our inability to record smells and play them back to be a blessing. David Isaacs, Sydney, Australia

A good question. I recently caught a whiff of aroma that to finance this important but neglected research a defrayed grant is now available from a stinking fund accrued by a certain perfume company, who are stench supporters of the concept and have even offered to bouquet pointments for applicants. But I was frankly incensed to learn that no one has scent for one, presumably because the task is regarded as too odorous. ThereisnoOwl

Light and sound are waves, that can be picked up and converted into electrical signals, transmitted, then reconverted back into waves again. Smell isn’t waves though, it’s actual particles in the air. A smellyvision would have to be essentially a teleporter that can recreate these particles and send them wafting towards your nose. Alex42

The mechanism by which smells register (signal transduction) is fundamentally very different to that involved for sight and sound. Anything that produces a sound wave can be heard. Anything that emits light within a certain span of the electromagnetic spectrum will be seen. But smell is actually the interaction of the odour molecules with a whole host of chemical receptors.

So to recreate a smell you need to do one of two things. You either know exactly how to trigger the correct chemical receptors in the right way to generate the odour sensation (probably by having to stick a probe of some in your nose), or you have to synthesise the odour molecule. More usually, an odour is generated by an array of molecules, which just adds to the synthesis complexity.

If you can appreciate just how difficult it is to synthesise fine chemicals, pharmaceuticals or biopharmaceuticals, then you can begin to understand just how difficult it would be to have a machine that generates the actual odour.

There has been progress in developing olfactory sensors, devices comprising an array of sensors upon which odour molecules make a characteristic imprint to allow their identification. In some distant future this could develop into a probe that could stimulate the olfactory sensors in your nose in a particular way to generate a desired effect. Hak_a_dalan

Ultimately, the nose is connected to the nervous system and there is some kind of neural signalling going on. The whole molecular thing could be bypassed if we gained the knowhow to generate the resulting nervous system signals. This is probably a better approach to concentrate on, since it would be applicable to touch, vision and hearing etc. AuldGrumpy

Every time you eat a processed foodstuff with “nature identical” flavouring, you are tasting a recording of that flavour. The strawberry-flavoured filling in that doughnut has never been near a strawberry. Some scientist identified and made a record of the particular proportions of particular chemicals that give a strawberry its taste, and now the doughnut factory copies that recording in a big shiny vat, stuffs the result into a doughnut and plays it back on your taste buds. SpoilheapSurfer

Maybe that’s not exactly a recording though … more like a tribute band? SylDaiPou

Having had an egg vindaloo on Friday I can categorically state that I have recorded and communicated the “smell” of the said curry over the course of the week. The quality of reproduction is hardly Bose, but it makes up for it in sheer raw volume. NIXXXX

An endless range of smells would be required to support any given subject, and would need to disperse almost as quickly as they were called into being. But they are not needed as our wide imagination provides all the smells known to us as needed, and instantly dispersed when done with. Derek Sykes

Film producers have in the past attempted to catch the nose as well as the eye with such odour-dispensing gadgets as AromaRama and Smell-O-Vision. While these had to depend in some cases on air-conditioning units, in lieu of scratch-and-sniff cards, a Japanese telecom company in 2006 was able to enhance a film with scents using an internet server. Perhaps a bells-whistles-and-smells AI robot in the future, or even an app, will finally bring us all to our senses. Richard Orlando, Quebec, Canada

The combinatorial explosion at both ends of the process. The explosion of complexity in the creation of a unique smell … all those bloody chemicals and their interactions … boggles the mind. Then when one considers the way the body transmits and interprets these sensations … yet more mind-boggling complexity. Oh, and then there’s the cost of modelling all of this … oh, and then the gap between the observable parts of this process and the subjective experience of perception. UncleMartin

You ask an interesting question, which reminded me of a visit to Monet’s garden in Giverny. Beforehand, I did a little study of his work with my two children. On walking into the water garden the first thing we noticed is the paintings lack the sounds and smells of the garden. We decided all artwork should come with those other sensory experiences to be completely appreciated. We noted how creating the smells would be rather tricky as it was a complex combination of things. I guess a well-funded biochemist could come up with the molecular structures of the various airborne particles and others could then 3D-print the molecules in a laboratory, but the cost, I imagine, would preclude it becoming mainstream. Having said that, when I see the prices musos are prepared to pay for excellent sound quality possibly some “nosos” would be prepared to pay for excellent smell quality. Teemytooks

A recent rereading of À Rebours reminded me that Huysmans envisaged a scent organ. It had an array of scents laid out like organ pipes and operated by a keyboard. It would only be a small step to replace the keyboard with a digital controller, or, for those of a steampunk tendency, a piano roll. But I preferred his mouth organ – a similar device, but using liqueurs and spirits rather than scent. seedysolipsist

You could quite easily do it but it might be expensive. Mass spectrometry can show what’s in a certain smell and from that it can be artificially created. 12345BOLLOCKSaeht443

Doesn’t gas chromatography do that? I suppose “playing the smell back” is still problematic. I think my dog would like a smell album rather than a photo album. little_john_fothers

Scratch-and-sniff is the closest you’re likely to get, or something similar to a perfume sample embedded into a page of a magazine. Recreating electromagnetic waves is easy, producing particles is much more difficult, so you would have to store the smells, rather than reproducing them. beneboy303

I once did the Jorvik tour in the York Viking Centre, late on a summer’s day. Each tableau comes with its own distinct “scent” released when each train stops at the point of interest. When the train stopped by the man using the privy, the realistic aroma, built up over many hours, was overpowering. I have not returned since. Issuing visitors with their own scratch-and-sniff card might have been a safer option. HemingfieldTwit

Probably the biggest reason, apart from the technical difficulties involved in recreating smell, is the simple lack of utility that olfactory reproduction provides. Necessity would not be the mother of this invention. hardyfool

The answer is probably simply that no one has yet seen a way to make money from smells, but … smell is so very closely related to taste. They involve taking molecules into your body, allowing a physical reaction within your own body to take place. Obviously the body reacts to sound and light waves – the beating of sound on the eardrum, the pinging of rods and cones at the back of your eyes – but smell and taste feel significantly more intimate somehow, more personal. An unfortunate smell lingers in the nose and throat and is perilously related to the need to vomit, to cough, to gag; we are pre-programmed to react very badly to dubious tastes and smells because of the risk of poisoning ourselves. Any argument to record and play back smells would need a very convincing economic argument. Northlondonhousewife

That’s like asking “why can’t we record or play back cheese?” Smell is actual stuff, not just waves in a medium. UnevenSurface

Bill Bryson, in his book The Body, explains the complexity of the sense of smell. A scientist describes a hormone called androsterone, which one-third of people smell as urine, one-third sandalwood and one-third cannot smell at all, to show how complicated smell is. MtEden

Smells have been tried. Films came with scratch-and-sniff cards and instructions to release the odours at certain points in the film. Devices in cinemas to release scents were tried in the 50s and 60s. The principle is reasonable in that any show design can include scent, just as it can include lighting and sound effects. However, sound and lighting can be reproduced repeatedly at little additional cost once the equipment is installed. Smell needs stocks of specific chemicals, each scent in each run adds to the cost. The financial model of the cinema is that there are premium payments available for first runs, but every subsequent showing needs to gather punters likely to pay less. Revenue drops to the level small-scale cable operators are able to pay, and any additional costs, such as scents are not going to be covered. Which all leads to the basic calculation that there are more cost-effective ways to improve recordings than adding smells. leadballoon

The human nature is to implicitly desire storytelling; our natural attempts to explain the universe around us were to construct stories of gods; modern advertising is not happy just trying to make products appealing but talks of the need for narrative around them.

Video games and even porn often have rudimentary and entirely superfluous plot, just to fulfil that need for stories that explain plumber and pizza-delivery misadventures.

Visual (even still) and auditory arts lend themselves to storytelling. But you simply can’t tell a story with just smells – at least with human’s rudimentary olfactory abilities – and so we have never found the need to record or play them back (ironic given how evocative they can be).

There have been attempts to weave smell into the movie experience, but like 3D it has never really got past the novelty stage, simply because while both add to the experience, they add nothing to the narrative and so, ultimately, audiences find them unnecessary.

Another factor is, even should smell be intrinsic to any plot, if necessary you can describe a smell visually and orally. But you can’t describe a sight or sound with smell. HaveYouFedTheFish

Be careful what you wish for. Read this! SimonGhent

I think the whole idea stinks! SimBee

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